Load-Independent Class-E Rectifier with Variable Gain and Fixed Input Reactance

In this research, we propose a variable-gain load-independent class-E rectifier with fixed input reactance for wireless power transfer (WPT) system. Featuring an adjusting network, the proposed rectifier can adjust its voltage gain to maintain a constant output voltage against load variations and coil misalignment, eliminating the need for additional regulators. Based on equations derived from circuit analysis, we present a design method to achieve the zero-voltage switching (ZVS) condition, ensuring high efficiency even at multi-MHz frequencies. Additionally, the input reactance of the proposed rectifier remains fixed, which is beneficial for maintaining ZVS of the inverter. To validate the design method, a WPT system at 6.78 MHz was built. The experimental results confirmed the successful voltage-gain adjustment to compensate for coil misalignment. Furthermore, load-independent ZVS and fixed input reactance were achieved, demonstrating the effectiveness of the proposed rectifier.